Convert the characters &, < and > in string s to HTML-safe
sequences. Use this if you need to display text that might contain such
characters in HTML. If the optional flag quote is true, the characters
(") and (') are also translated; this helps for inclusion in an HTML
attribute value delimited by quotes, as in <ahref="...">.

Convert all named and numeric character references (e.g. &gt;,
&#62;, &#x3e;) in the string s to the corresponding Unicode
characters. This function uses the rules defined by the HTML 5 standard
for both valid and invalid character references, and the listofHTML5namedcharacterreferences.